The present invention relates to fluid pressure control apparatus and/or process for controlling a fluid pressure with a solenoid valve.
In the case of a solenoid valve for controlling a fluid pressure, the behavior of the output pressure of the solenoid valve with respect to a solenoid drive current exhibits hysteresis between the current increasing side and decreasing side. Therefore, a Japanese patent document JP2003-294126A proposes a solenoid valve control system using predetermined measurement map of actual values of the output pressure for each of current values, obtained by measurement when the current is increased until the output pressure is increased to a highest pressure value and then the current is decreased until the output pressure is decreased to a minimum setting equaling zero. This solenoid valve control system controls the solenoid drive current by using a characteristic map representing a relationship between an output pressure and an average current between an increasing side current value and a decreasing side current value for the same current value, calculated from the predetermined measurement map.